1. Field of the Invention
The present invention relates to a voltage level generating device, and more particularly, to a common voltage level generating device which can reduce the circuit layout area in a driver integrated circuit (IC) of a display device, and can select different output of voltage level in order to reduce the power consumption of the display device.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 shows a simplified circuit diagram of a conventional common voltage level generating device 100 utilized in a driver integrated circuit (IC) of a display device (not shown) in accordance with a prior art. As shown in FIG. 1, when the conventional common voltage level generating device 100 is required to output a common voltage level VCOM, the conventional common voltage level generating device 100 uses a digital-to-analog converter (DAC) 110 to generate a first reference voltage level VREFH, and then generate a first voltage level VCOMH via a first buffer 120, wherein the first voltage level VCOMH will be between a first specific voltage level DDVDH and a ground voltage level AGND. In addition, the conventional common voltage level generating device 100 uses the DAC 110 to generate a second reference voltage level VREFL, and then generate a second voltage level VCOML via the first reference voltage level VREFH, resistor units R1, R2 R3, and R4, an operational amplifier 130, and a second buffer 140, wherein the second voltage level VCOML will be between a second specific voltage level VCI and a third specific voltage level VCL.
In the conventional common voltage level generating device 100, the resistor units R1, R2 R3, and R4 having high resistance value are required in order to reduce static current consumption. In addition, the conventional common voltage level generating device 100 has to use at least two buffers and an operational amplifier, and thus the conventional common voltage level generating device 100 has a disadvantage of requiring large circuit layout area.